Textile bobbin



April 1969 T. G. CRAWFORD 3,436,034

TEXTILE BOBBIN Filed Feb. 2'7, 1967 FIG. 3. 4|

WITNESSES INVENTOR W Thomas 6. Crawford.

ATTORNEY United States Patent 3,436,034 TEXTILE BOBBIN Thomas G. Crawford, Hampton, S.C., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 27, 1967, Ser. No. 618,843 Int. Cl. B65h 75/10, 75/12 US. Cl. 242118.32 7 Claims ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to plastic pirns, bobbins, and the like, for use in winding textile fibers.

For many years, the synthetic textile yarn industry has used a steel bobbin or pirn for draw twisting nylon and similar synthetic yarns. Originally, a paper cover was placed over the steel body to protect the yarn from contaminants and to prevent fiber discoloration. Recently, covers or sleeves of ABS (acrylonitrile-butadiene-styrene) resin overcame some of the difiiculties encountered with the paper covered steel bobin. The covers, however, have a relatively short life. Damaged or worn covers must be replaced or reconditioned and a substantial amount of labor is devoted solely to this work in the textile yarn plants.

Some of the foregoing problems were solved and other advantages were obtained by making bobbins or pirns with laminated plastic tubular barrels, as for example, the resinous plastic pirn described and claimed in US. 2,879,010, assigned to the assignee of this invention. With the advances to higher strength synthetic fibers, larger packages of fiber on the bobbins and higher rotative draw twisting speeds, greater stresses are now being imposed on the tubular barrels. In order to prevent large deflections that may cause the tubular barrel to take a permanent set when subjected to the higher compressive forces, it has become apparent that a higher strength tubular member would be advantageous.

Other problems have been encountered when the heretofore known pirns, both metal and plastic, have been subjected to these higher compressive forces. The higher compressive force causes a greater deflection of the tubular barrel wall which, in turn, causes the internal guide bushing to bind on the winding spindle. The binding, of course, makes it difiicult to remove the pirn or bobbin from the winding spindle. Improved surfaces that are more resistant to abrasion and scratching with the highly desirable properties of good yarn release without sloughing or slippage in addition to good starting would also be considered advantageous. In order to prevent damage to the yarn, it is also essential that the pirn or bobbin be designed to preclude the possibility of snagging or trapping of yarn.

Summary of the invention An object of the present invention is to provide a pirn or bobbin that will resist crushing, deformation and ex- 3,436,034 Patented Apr. 1, 1969 cessive deflection when subjected to high compressive forces.

A further object of the invention is to provide a pirn having an internal spindle guide bushing that will not bind on the spindle when high compressive forces are imposed on the tubular barrel of the pirn.

Yet another object of the invention is to provide a pirn having surfaces that are extremely resistant to abrasion and scratching, that will give good yarn release without sloughing or slippage in addition to good starting properties.

A further object of this invention is to provide a pirn or bobbin having drive and end bushings that will not trap or snag the yarn.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

Briefly, the foregoing objects are accomplished by impregnating the fibrous sheet of the tubular barrel with an epoxy-modified cresylic acid phenol-formaldehyde resin. Such barrels have a lower deflection when subjected to high compressive forces. The internal spindle guide bushing has slots and a frustoconical portion that relieve the stresses so that a close tolerance may be maintained about the spindle without danger of binding on the spindle.

Brief description of the drawing For a better understanding of the nature and objects of the invention, reference may be had to the following drawing, in which:

FIGURE 1 is a vertical cross section through a pirn or bobbin of this invention;

FIG. 2 is an isometric view of an internal spindle bushing in accordance with this invention;

FIG. 3 is an exploded view illustrating in detail the reverse tapers on the barrel end and the drive end bushing of the pirn; and

FIG. 4 is an end view of the pirn illustrating a suitable recessed drive engagement configuration molded into the drive end bushing of the pirn of this invention.

Description of preferred embodiments In the present invention, an epoxy modified cresylic acid phenol-formaldehyde resin is used to impregnate and coat .a fibrous sheet material that is wound into tubular form. After the resin is cured to its solid infusible state, the fibrous sheet material is bonded into a strong unitary tubular member. The tubular member of barrel forms the body of the pirn or bobbin and has a higher strength than tubes impregnated with the heretofore employed unmodified phenol-formaldehyde resins. Moreover, the epoxy modified cresylic acid phenol-formaldehyde impregnated barrels may be exposed to higher compressive forces than the unmodified phenol-formaldehyde impregnated tubes, without taking a permanent set.

Because a large amount of resin is present in the impregnated fibrous sheet material, the resin, as well as the sheet material, has an effect on the machinability of the tube and the type of surface produced by the machining. Tubes inpregnated with the epoxy modified cresylic acid phenol-formaldehyde resins can be finished on a centerless grinder to produce surfaces that have good yarn release without sloughing or slippage. The tube also has good starting properties, i.e., the initial winding of yarn onto the tube may be accomplished without trouble. In the present invention, the fibrous sheet material may be paper, preferably a high strength kraft paper having a thickness from about 2 to 7 mils.

Most pirns or bobbins have an internal bushing so the pirns may be easily placed or guide dover the drive spindle. In order to minimize vibration and torque loading on the rotating spindle, particularly with unbalanced yarn loads, it is desirable to have only a small clearance between the internal bushing and the spindle. As yarn is wound onto the pirn, particularly high tenacity synthetic yarns, the tubular wall is subject to. a high compressive force. The tubular walls of the pirns of this invention, while they do not take a permanent set, nonetheless to deflect to some extent, as do the tubular walls or barrels of all pirns. The deflection in the tubular wall causes the heretofore employed internal bushings to deflect and, where the clearance is small, to bind on the spindle. This is particularly true of the heavy walled internal guide bushings.

In plastic pirns, this problem of binding is compounded by the tendency of the tubes of barrels to shrink with age. In the prior art, either the clearances between the guide bushing and spindle had to be sufliciently large to accept the possibility of vibration with unbalanced yarn loads, or with small clearances, the possibility of binding between bushing and spindle. The internal bushings employed in this invention are designed so that deflections in the barrel do not cause the bushing to bind on the spindle even with small clearances, in the order of 2 to 5 mils. In the bobbins or pirns of this invention, the spindle bushing must be substantially flexible. The bushings are formed from a resinous thermoplastic material, such as nylon, that has substantial flexibility. A first cylindrical load bearing portion of the bushing engages the interior wall of the pirn barrel. The first cylindrical portion is connected by a frustoconical portion, which serves as a stress-relief means, to a second smaller cylindrical portion that is closely spaced to or is in contact with the spindle when the bobbin is in place.

The cylindrical load carrying portion has at least one slot cut therein. The slot serves a dual function. It permits the bushing to be press-fitted into the barrel so that it is firmly retained with a substantial interference, of about 5 to mils, but without the danger of forming cracks in the bushing. It also serves to take up a portion of the barrel wall deflection without passing it on to the frustoconical and smaller second cylindrical portion of the bushing. More than one slot may be employed and three equally radially spaced longitudinal slots are pre ferred. It should be understood that the slots may be disposed at other angles, if desired.

Substantial deflections in the barrel and in the first cylindrical portion will be transmitted to the intermediate frustoconical portion of the bushing. The frustoconical design of this intermediate portion will not, however, permit a similar deflection in the second cylindrical portion of the bushing. Indeed, under high compressive forces and deflections, because of the design of the intermediate portion of the bushing, the tendency will be for the clearance between the spindle and the small cylindrical section to increase slightly.

Referring now to FIGURE 1 of the drawing, there is illustrated a pirn 10, in accordance with this invention. The pirn 10 comprises a laminated tubular member or barrel 11 composed of plural turns of paper impregnated with a solid cured infusible epoxy modified cresylic acid phenol-formaldehyde resin. The interior 12 of the tube may be machined or ground to the desired inner diameter but the finish obtained from chrome plated mandrels is ordinarily satisfactory. The exterior surface 13 of the tube is finished to the desired outer diameter on a centerless grinder. A spindle guide bushing 20, having a diameter from about 5 to 10 mils greater than the inner diameter of the tube, is pressed into the interior of the tube, intermediate the ends of the tubs, so that the spindle projects therethrough.

A drive bushing is mounted in the bottom end of the tube 11. The stepped portion 41 is pressed into the bottom of the barrel or tube and may have a diameter up to about 5 mils larger than the inner diameter of the tube. If desired assmall amount of adhesive may be employed between the contacting or mating surfaces.

The drive end bushing has a recessed shape 43 appropriate to engage a spindle drive keying configuration 31 so that the pirn may be rotatably driven. A suitable recessed drive configuration 43 is illustrated in FIG. 4 of the drawing. It should be understood, however, that other drive configurations may be employed.

At the upper end of the tube 11, an upper end member, commonly called an identification end, is press-fitted into the tube. The identification end bushing 50 is designed so that it does not project above the tube 11. The absence of projections is desirable as it eliminates or reduces the possibility of yarn being snagged or trapped on the pun.

The tubular member or barrel 11 of the pirn of this invention can be made, for example, by passing unbleached kraft paper having a thickness of 6 mils and a basis weight from 49 to 54 (24 x 26500) through a path of epoxy modified cresylic acid phenol-formaldehyde varnish and then through squeeze rolls to leave a resin solids content of 50 to 60%. The impregnated paper has a greenness or flow of 8 to 12% after the resin has been B-staged in an oven with temperatures varying from 210 to 270 F., the paper passing through the oven with a dwell time of about 2 to 10 minutes. Greenness is determined by the test described in US. Patent 2,383,430.

To secure the desired high strength pirn barrel, the resinous impregnant must have from 2 to 6 parts of thermosettable epoxy resin per parts of cresylic acidphenol-formaldehyde thermosettable, resin. The laminates made from the copolymer product by reacting the resin mixture has great resistance to deformation under high loads and does not plastically deform under loads that would cause cresylic-phenol-formaldehyde laminates to deform. Laminates embodying the copolymer resin of this invention markedly resist abrasion and scratching. The mixed resins are dissolved in organic solvents, applied to paper or cloth dried to a B-stage and the treated sheet wound on a mandrel into a tube and cured to a thermoset state.

Outstanding tubes have been made, for example, with a blend of about four parts of a liquid aromatic base epoxy resin having an epoxide equivalent weight of about 175- 210 (for example Shell Chemical Company, Epon 828), about 0.3 part of a wetting agent (Nalco 212, National Aluminate Co.), 100 parts of a cresylic acid phenolformaldehyde composition described hereinbelow, together with suflicient methanol to give a liquid impregnating composition having viscosity of about 30-80 centipoise at 25 C. and a recoverable solids content of about 51 to 53%, by weight. The cresylic acid phenol-formaldehyde composition is made by charging a vessel with parts of cresylic acid, 10-20 parts of phenol, 103-115 parts of formaldehyde, 0.3 part of ethylene diamine and 1.5 parts of ammonia, by weight. The charge is refluxed for 30 minutes the mixture being vacuum dehydrated at the end of this period to remove substantially all of the water, until the reaction product is clear and dry to touch at room temperature. When that point is reached about 35 parts of methanol and about 35 parts of toluol, by weight, are added to provide a resinous composition having a viscosity of 60 to 175 centipoise at 25 C. with a recoverable solids content of 57 to 59%, by weight.

The tubes are made by passing the resin impregnated paper material over a roller heated to a temperature from 135 to 175 C., for instance over a 12-inch roll at a speed of 50-120 inches per minute, to soften the B-staged resin. The heated paper is wound on a metal mandrel heated to a temperature of 100120 C. During winding a pressing roller exerts a uniform pressure of about 9 to 12 pounds per linear inch along the length of the tube. Maximum web tension is maintained on the material during winding to assure a tight tube and a good bond. After the tube is rolled to the desired wall size, it is baked for 2 to 4 hours at C. to fully cure the resin to a thermoset stage.

The drive end and identification end bushings 40 and S0,

respectively, are preferably molded or otherwise formed from a thermoplastic resinous material such as nylon, polyethylene, polytetrafluoroethylene or polystyrene. These bushings may also be molded from thermosetting resinous materials. The internal guide bushing 20, however, should be molded only from a thermoplastic resinous material, for example nylon, polyethylene and polystyrene, to give the desired flexibility.

Referring now to FIG. 2 of the drawing, the bushing has a first cylindrical portion 21 which is adapted to engage the interior of the pirn barrel. A plurality of slots 22 are cut into the cylindrical portion 21 to permit a good press fit without cracking the material and to minimize deflection of the second smaller cylindrical portion 24 when the pirn tube is subjected to mild compressive forces. The fnistoconical section 23 presents an inward deflection of portion 24 when the pirn wall and the portion 21 of the bushing are subjected to high compressive forces. Accordingly, the diameter of the portion 24 may be such that only a small clearance, for example 2 to 5 mils, or light moving contact, exists between it and the drive spindle. The pirn will be easy to remove from the spindle even when subjected to high compressive forces.

Referring now to the exploded view of FIG. 3, it can be seen that the drive end bushing 40 is press fitted into the lower end of the barrel 11. The stepped cylindrical outer wall 41 has a free diameter from about 5 to 10 mils greater than the inside diameter of the barrel. The abutting flange surface 42 has a reverse taper that may vary from 2 to 8". In this example, the reverse taper is 5". The end surface 14 of the barrel may also have a reverse taper of from 2 to 8 and in this example is also 5. The reverse tapers on the bushing and barrel insure a mating of surfaces 14 and 42 so that yarn is not trapped or snagged therebetween. The larger cylindrical portion 44 is preferably scaled so that it will not be wider than the diameter of the pirn barrel.

As seen in detail in FIG. 4, the interior of the portion 44 has a molded open drive recess 43 of a general hexagonal shape. Three arcuate and three fiat sections, 45 and 46, respectively, are joined together in the general hexagonal shape. The recess extends up to the flat wall 47 (FIG. 3) which rests on the spindle drive 31 (FIG. 1) when the pirn is in place. The spindle drive has the same general hexagonal configuration but is sufliciently smaller than the molded recess so that the pirn or bobbin may be easily placed thereover.

The identification end bushing into the top end of the barrel 11. The diameter of the cylinder 51 is from about 5 to 10 mils greater than the inside diameter of the barrel. The end of the bushing has an angular flange 52 that mates within an appropriate chamfer 53 at the end of the barrel so that no part of the bushing extends beyond the barrel when the bushing is in place.

The described pirn or bobbin is especially suitable for use in winding synthetic fibers, such as nylon. The high tenac ty of a winding of such fibers imposes high compressrve forces on the pirn. Any fine cuts or scratches on the barrel may be easily removed by light sanding. The pirns of this invention are considerably lighter in weight than metal pirns and may be reused many times with little or no maintenance.

Since numerous changes may be made in the abovedescribed pirns or bobbins and diflferent embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying 50 (FIG. 1) is pressed drawing, be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high strength textile bobbin adapted to cooperate with a spindle having means to rotatably drive the bobbin comprising, in combination, (1) a tubular barrel consisting essentially of plural plies of a fibrous sheet material impregnated with a solid thermoset resin derived from a blend of from about 2 to 6 parts of epoxy resin and parts of cresylic acid phenol-formaldehyde resin, by weight, (2) a drive end member pressed into the lower end of the barrel and having means to engage the spindle drive means, (3) a guide bushing pressed into and disposed entirely within the barrel intermediate the ends, the guide bushing having a first cylindrical portion firmly engaging the barrel and a second cylindrical portion closely fitting the upper end of the spindle and (4) an identification end bushing pressed into the upper end of the barrel.

2. The bobbin of claim 1 wherein the identification end bushing has an angular flange and the upper end of the barrel has a recess to accommodate the flange when the end bushing is pressed into the barrel so that the end bushing does not extend beyond the upper end of the barrel.

3. The bobbin of claim 1 wherein the guide bushing is formed of a thermoplastic resinous material and said first and second cylindrical portions are joined together by an intermediate frustoconical section, the guide bushing having longitudinal slots disposed only in the first cylindrical portion thereof.

4. The bobbin of claim 3 wherein the thermoplastic resinous material is selected from the group consisting of nylon, polyethylene and polystyrene.

5. The bobbin of claim 4 wherein the thermoplastic resinous material is nylon.

6. The bobbin of claim 5 wherein the drive end member and the upper end bushing are also molded from nylon.

7. A textile bob'bin adapted to cooperate with a spindle having means to rotatably drive the bobbin comprising, in combination, (1) a tubular barrel comprising plural plies of a fibrous sheet material impregnated with a solid thermoset resin, (2) a drive end member pressed into the lower end of the barrel and having means to engage the spindle drive means, the drive end member having a flange portion contacting and mating with the lower end of the barrel, both flange portion and barrel end having reverse tapers from about 2 to 8 degrees so that the mating area does not trap yarn, (3) a guide bushing pressed into and disposed entirely within the barrel intermediate the ends, the guide bushing having a first cylindrical portion firmly engaging the barrel and a second cylindrical portion closely fitting the upper end of the spindle and (4) a bushing pressed into the upper end of the barrel.

References Cited UNITED STATES PATENTS 2,879,010 3/1959 Crawford 242-11832 3,000,590 9/1961 Dunlap et al. 242118.3l 3,054,428 9/ 1962 Crawford 242118.32 X 3,300,153 1/1967 Fenn 24246.21

FOREIGN PATENTS Ad. 37,946 11/1930 France.

GEORGE F. MAUTZ, Primary Examiner. 

